Carbon dioxide has been used to kill microorganisms non-thermally, meaning that the mechanism through which such microorganisms are killed is not dependent on a high temperature. However, the methods using carbon dioxide are static methods, since after the conditions of the carbon dioxide were set, the conditions were held for a period of time to affect the microorganisms. Thereafter, the treatment was stopped. Supercritical conditions, where carbon dioxide exists only as a supercritical fluid, have also been tried. These methods, too, were static, meaning that once the conditions were set, the carbon dioxide was allowed to affect the microorganisms, and then, the carbon dioxide treatment was stopped. While such treatments did achieve some reduction in microorganisms, there is still much to learn in the way of using carbon dioxide to reduce microorganisms.